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August 01, 2007



Looking at http://www.greenercars.com/highlights_greenest.htm it looks to me that the article you quoted got it wrong about which car has better fuel economy.

Kit P

Clee go back and read the story again. Look for 'and reduced emissions'.


Well duh, I didn't say they were wrong about the natural gas car having reduced emissions. It said "and", not "or", so both halves of the sentence need to be true for the whole to be true.

Actually this started when a friend asked how does one compare fuel economy between cars which use different fuels. I assumed they did it by BTU content of the different fuels, but that's not really clear from note c of the chart.

Harvey D

How would a NG Prius compare as far as GHG and fuel efficiency?

George Bruce

Meanwhile, back on the plug in ranch:


Carl Hage

The article "Which is Greener, a Hybrid or Natural Gas Car? " is misleading. The answer is "The car from California". See fueleconomy.gov for (new) fuel consumption, GHG emissions, and pollution category (details available too).

The California versions have the same AT-PZEV ratings, whereas in other states the Civic-CNG has a lower emissions rating (still not as good as either California model). The Prius has slightly lower GHGs, 4.0T vs 5.4T/15K-mi. Of course, a CNG car uses much less Oil.

Unfortunately, the "Green" scores I've seen listed at greenercars.org use the non-California ratings.

Yes, the "Gasoline Gallon Equivalent" of CNG is based on the equivalent heating value (BTUs) of burning the fuel. The EPA numbers show a CNG Civic is 28MPG vs 29 for gasoline, but CNG has less CO2/BTU than gasoline, so the CNG Civic is better than the 6.3T of a gas Civic.


technofossil, could you give us a more specific URL? I couldn't find any details on the Civic GNG equivalent mpg or emissions rating on fueleconomy.gov


er, Civic CNG


Clee, you just click 2007, Honda, Civic, and the CNG model is the last one on the list: http://www.fueleconomy.gov/feg/calculatorCompareSideBySide.jsp?column=1&id=23862

28mpg? Unless it emits <1/2 the C02, I don't see how it "beats" a Prius.


Thanks. You've got to interpret the words. The Honda Civic CNG beats the Prius in lower emissions because of the smog-forming SOx and NOx emissions. Natural gas burns cleaner than gasoline.

As for greenhouse gas emissions, technofossil pointed out that the Civic CNG emits less GHG than the regular Civic (non-hybrid), but more than the Prius.


Does anyone have a Civic GX and how do you like it? Is it troblesome to fill up? Thanks


I have a 2008 Civic GX. We bought the home filling station FMQ-2-36 (Fuelmaker.com). We love the car $1.50 gal 36+ mpg and now the gas has gone over $3.70 gal we are actually saving money after payment. Plus the GX is the LX trim and it has everything...


CNG is cheap fuel and better alternative no doubt.
CNG corridors can enable large scale substitution of petrol and diesel run commercial and personal vehicles through an extensive distribution and dispensing infrastructure.

for more read


ONGC is the mail Oil and Gas producer for India and one of world's Largest companies.

Used Cars

terry g

In order to solve the energy/global warming problem, we have to select the right technologies and supporting infrastructures, as well as a technology that isn't dependent on foreign supplies, can we agree on that? All fossil/biofuel candidates produce CO2, possibly methane, and other noxious gases and particulates. CNG, for example, is a good low CO2-polluting fuel, but since it is the highest methane-polluting of the fuels discussed, and since methane is a 25x stronger greenhouse gas than CO2, we would just be going from the frying pan to the fire. The only fuels that I can think of that would be clean enough would be hydrogen and electricity, produced at a central location to keep carbon footprint down. The cleanest electricity production is desert solar hot oil facilities. At these or other centralized facilities, hydrogen could then be produced and stored/distributed, if we needed that. In the meantime, to reduce CO2, we can marry submarine technology (sodium peroxide and CO2 react to produce sodium bicarbonate and O2) and CO2 collection technologies. We could then sequester/use the sodium bicarbonate. There is no perfect solution, but a solution begins by understanding that for every exothermic reaction benefit that we get (coal, oil, gasoline, nuclear, etc.) we have to pay for that with a (sometimes expensive) endothermic cleanup. Why not use free energy to pay for all the enothermic cleanups we must undergo? In any event, GONE MUST be the days of rapine progress at the expense of the environment.

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